Question

I have an NSDictionary. It has keys and objects.

For the purposes of simplicity the keys are Question numbers and the objects are calculated Answer scores.

Now how I did it before was that I set the answer score as the keys and the question numbers as the objects. This way I could get an array of allKeys from the dictionary, sort it and then do something similar to:

for(NSString *string in tempArray){
  NSLog(@"%@",[dictionary objectForKey:string]);
}

The (stupid – on my part) problem that I have now encountered however is that (obviously… duuhhh) the keys need to unique, and therefore when the calculated answer scores are the same, only one answer gets output!

I need a solution to this. In PHP you can multisort arrays. I was wondering if there was some similar solution in objective-c or indeed if someone had a better answer?

Any help here would be much appreciated.

Thank you.

Answer 1

One solution is to store the answer scores using an array of dictionaries containing only two key-value pairs. One key is the question number (or however your questions are tagged, i.e. “Q1.1”), while the other key is the actual answer score. For example:

static NSString * const QuestionKey = @"questionNumber";
static NSString * const AnswerScoreKey = @"answerScore";

NSMutableArray *allAnswers = [NSMutableArray array];

for (int i = 0; i < 20; i++)
{
    // fill allAnswers array with random data
    NSDictionary *answer = [NSDictionary dictionaryWithObjectsForKeys:
        [NSString stringWithFormat:@"Q%d", i], QuestionKey,
        [NSNumber numberWithInt:rand()], AnswerScoreKey,
         nil];

    [allAnswers addObject:answer];
}

// sort the allAnswers array based on score, highest first
NSSortDescriptor *sortDesc = [NSSortDescriptor sortDescriptorWithKey:AnswerScoreKey ascending:NO];

[allAnswers sortUsingDescriptors:[NSArray arrayWithObject:sortDesc]];

for (NSDictionary *answer in allAnswers)
{
    NSLog(@"Question: %@, AnswerScore: %@", [answer objectForKey:QuestionKey], [answer objectForKey:AnswerScoreKey];
}

Disclaimer:

Untested and uncompiled code. Theory only.